Logic / Memory

A variety of memory and logic devices, including DRAM (dynamic random access memory), SDRAM (synchronous dynamic random access memory), Flash memory (NAND or NOR), CPU (central processing unit), GPU (graphics processing unit), etc., are widely used in computers, digital music players, gaming devices and mobile internet devices. For instance, since SDRAM was introduced to computers, further generations of SDRAM (DDR1, DDR2 and DDR3) have entered the mass market, with DDR4 currently being designed and anticipated to become available in the coming years.

Wafer level packaging (WLP) combines flipchip (FC) technology with surface mount technology (SMT) and ball grid array (BGA), where all processes are completed directly on the wafer before the chips are singulated for FC assembly. Key related technologies include redistribution layer (RDL), repassivation and bumping. Lithography techniques for metallization, such as RDL, pillar and bumping, are crucial for WLP. The IC industry is starting to adopt WLP for various applications, mainly driven by RF devices. Fan-out WLP is recently developed and adopted by many wireless manufacturers for lower thickness, smaller footprint and higher routing density. TSV is becoming part of WLP technology as it enables the shortest and greatest number of interconnections.

Based on well established double side mask alignment systems, EV Group offers a product portfolio which covers all essential process steps for backend lithography, such as wafer bumping, creation of RDL and via etching masks, via bottom opening processes as well as lithography performed on thin or temporary bonded wafers. Such wafers may be aligned based on alignment keys on the wafer backside or in the (temporary) bond interface, where mask aligners with backside microscopes, transmissive or reflective infrared alignment capabilities are applied. The systems are available in semi-automated configurations for process development and smaller scale manufacturing requirements, while fully-automated system configurations, running cassette-to-cassette processes, are optimized for high-volume manufacturing.